This application claims priority under 35 U.S.C. xc2xa7xc2xa7 119 and/or 365 to Appln. No. 9904481-0 filed in Sweden on Dec. 8, 1999; the entire content of which is hereby incorporated by reference.
The present invention relates to a safety arrangement in a package turning device of the type which turns selected packages which are conveyed on a conveyor path, the package turning device essentially comprising a piston and cylinder assembly with a piston rod disposed to move parallel with the conveyor path, a turning member and a gripping member.
Package turning devices of the type which turn selected packages being conveyed on a conveyor path are employed, for example, for turning one of the packages in a multipack in order, by such means, to conceal the bar code carried on the package. The bar code on each package contains, int. al., information on the price of the individual package and when the package is included in a multipack, this multipack will have a new bar code which indicates the price of the multipack unit. For example, the multipack may contain two or more individual packages.
Multipacks are often employed for single-use disposable packages of small volume for liquid foods, such as juices and fruit drinks. These single-use disposable packages are manufactured from a packaging laminate with a core layer of paper or paperboard to which are laminated different layers of thermoplastic and possibly aluminum foil (Alifoil). The packaging material, which most generally occurs in web form, is formed in a filling machine into a tube and is longitudinal-sealed. The tube is filled with the intended contents, whereafter it is transversely sealed and severed in the seals to form individual packaging blanks. The packaging blanks are finally formed and normally obtain a parallelepipedic configuration.
With filling, machines which are developed to work at increasingly higher capacity, it is a requirement that the distribution equipment, such as package turning devices, which normally accompany a filling machine have the same capacity. When the finished packages depart from the filling machine, they are conveyed on a conveyor path and in order to avoid the accumulation of packages, a turning device (where applicable) must be able to carry out the turning operation of selected packages while the packages pass along the conveyor path.
Turning devices for packages of the above-outlined type are available on the market and they generally consist of a pneumatic or hydraulic piston and cylinder assembly, with a reciprocating movement which is parallel with the conveyor path on which the packages are being conveyed. On the piston rod of the assembly, there is disposed a turning member as well as members for gripping the package. Turning devices of this type are well-known to those skilled in the art.
However, it has proved that a piston and cylinder assembly of a size which is suitable for executing the turning operation does not possess sufficient accuracy as regards adapting the speed of the piston rod to the conveyor path so that the gripping member can grip the package in the correct position. If the package is not gripped centrally, there is a risk that the package is overturned and thrown outside the conveyor path, or that it topples over and causes disruption in the distribution equipment. Piston and cylinder assemblies of this size have moreover proved to be sensitive to the environment in which they are placed. In the event of disruption in the distribution equipment, there is always the risk that the packages are ruptured and that the product sloshes or sprays out in its surroundings. Since the product, normally juices and fruit drinks, contains sugar, the result will be a tacky surface on those parts of the distribution equipment which have been subjected to product sloshing.
One method of solving this problem is naturally to employ a piston and cylinder assembly which is considerably more robust. By employing a more robust assembly, a higher degree of accuracy will be obtained for the movement of the assembly in relation to the conveyor path, and a more robust assembly is also more resistant to the environment in which it is to operate. However, the employment of a more robust piston and cylinder assembly entails that the risk of damage to the package proper and the equipment increases when there is a sudden operational stoppage in the distribution equipment. It must therefore be ensured that the machine stops immediately when this occurs. Operational stoppage may, for example, be because the movement of the gripping member is prevented in that packages topple over or that a foreign object intervenes.
One object of the present invention is to realise a safety arrangement which is triggered rapidly and distinctly.
A further object of the present invention is that it should not contain components which are sensitive to the environment in which the arrangement is placed.
These and other objects have been attained according to the present invention in that an arrangement of the type described by way of introduction has been given the characterising features that the safety arrangement includes an anchorage disposed on the piston rod of the piston and cylinder assembly, and a bracket which is disposed to support the turning member and the gripping member, the anchorage and the bracket being united in spring-biased fashion so that they enclose a cavity, and that an incoming air conduit and an outgoing air conduit are connected to the cavity, with a pressure guard disposed on the outgoing air conduit.
Preferred embodiments of the present invention have further been given the characterising features as set forth in the appended subclaims.